# Remote controls

**URL:** <https://boards.straightdope.com/t/remote-controls/518983>\
**Category:** Factual Questions\
**Created:** [November 26, 2009, 1:29am UTC](https://boards.straightdope.com/t/remote-controls/518983 "2009-11-26T01:29:50Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Patrick\_Mc](https://avatars.discourse-cdn.com/v4/letter/p/5e9695/32.png) [@Patrick\_Mc](https://boards.straightdope.com/u/Patrick_Mc)\
**Post date:** [November 26, 2009, 1:29am UTC](https://boards.straightdope.com/t/remote-controls/518983/1 "2009-11-26T01:29:50Z")

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What keeps remote automotive door lock frequencies to be different enough so that there are no duplicates?

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**Author:** ![Fubaya](https://avatars.discourse-cdn.com/v4/letter/f/c2a13f/32.png) [@Fubaya](https://boards.straightdope.com/u/Fubaya)\
**Post date:** [November 26, 2009, 1:48am UTC](https://boards.straightdope.com/t/remote-controls/518983/2 "2009-11-26T01:48:42Z")

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The frequencies don’t matter. The car and fob generate a list of random numbers (256 40-bit numbers I think) and sync the list. The fob sends a random number and the car checks it against the list.

See this: [How Remote Entry Works | HowStuffWorks](http://auto.howstuffworks.com/remote-entry.htm)

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**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\
**Post date:** [November 26, 2009, 3:00pm UTC](https://boards.straightdope.com/t/remote-controls/518983/3 "2009-11-26T15:00:26Z")

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Garage door openers work the same way. Unless you have one built in 1955.